Input: silead - list all supported compatible strings in binding document

The driver contains compatible strings for different models, but the DT
binding doc only lists one of them. Add the remaining to the document.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>